An element that can control current without moving parts, heated filaments, or vacuum gaps.

To free something from the binding action of ice by warming it to a temperature above the melting point of ice. Also, a warm spell when ice and snow melt.

An area of low barometric pressure, with its attendant system of winds. Also called a depression or cyclone.

A unit that represents one degree of deviation from a reference point in the mean daily outdoor temperature (usually 65

Not a linear function of the relevant variables.

The ratio of the actual amount of water evaporated into the atmosphere to the evaporative power. Also called relative evaporation.

Balance of the water resources of a region, comparing precipitation and inflow with outflow, evaporation, and accumulation.

The record of an aneroid barograph.

An ice coating with a consistency intermediate between glaze and rime.

Instrument for measuring the intensity of radiant energy. Its principle is based on the variation of electrical resistance, with the incoming radiation, of one or both the metallic strips which the instrument comprises.

Wind with a speed between 22 and 27 knots (25 and 31 mph); Beaufort scale number 6.

A vent used with pressure sensors to reduce the effect of wind on the pressure inlet. It is normally mounted remotely and connected to the sensor using airtight tubing.

A wind (or component thereof) directed down the slope of an incline and caused by greater air density near the slope than at the same levels some distance horizontally from the slope. Also called drainage wind and sometimes called katabatic wind.

A unit of heat originally defined as the amount of heat required to raise the temperature of water through one degree centigrade (the gram-calorie or small calorie), but this proved to be insufficiently precise. The 15

Binary Coded Decimal. A coding system in which each decimal digit from 0 to 9 is represented by a 4-digit binary number.

An early and once universal name for the mercury barometer.

A wind blowing in a direction opposite to the heading of a moving object, thus opposing the object's intended progress; the opposite of a tailwind.

force wind-Wind with a speed above 64 knots (73 mph); Beaufort scale numbers 12 through 17.

The unit of acceleration in the centimeter-gram-second system of units, equal to one cm per sec2. Commonly used in gravimetry.

Wind with a speed between 11 and 16 knots (13 and 18 mph); Beaufort scale number 4.